if your stugling to find interesting things to do with your PSP i feel quite sorry for you.... mine gets so much love cos it does so much good stuff!
PSPSpectrum (the zx spectrum emulator) could keep me going alone, and the "roms" - which arent roms at all but tape images - are only about 30-70 K in size!!
thankfully games were actually a a challenge back then, so they should keep you going a long time
most of these are LEGAL to download from
http://worldofspectrum.org - since i still own my original tapes i have copies of all the ones listed not on the site :)
and that's just the one emulated 8--bit system!
there's also 1001 Amiga games to play on pspuae, gameboy games (although i only like a handful - Kirby's Pinball Land being a cut above anything else on the system) on Rin , Megadrive on DGen and it would seem *even* the C64 has some good games to play on psp-Vice.
i'm still on emualtors, and havent even begun to list the good commercial PSP games (although i admit there arent too many, but those that are good - are very good!)
still struggling to find abandonware games? look on
www.planetemu.net and remember that "telechargement" is french for "download"